I’m really stuck on this so any input gladly received.
I have some simple products that have custom options that are additional gifts. These additional gifts are not actual catalog products but do need to be charged tax (UK VAT) when added to an order. I know that custom options themselves are not taxable outof the box so I thought I would relate them to an actaul product that I created whcih is not visible in the frontend so it can’t be bought separately. I added teh SKu of this new product in the custom options fields but obviously they still don;t collect tax. I then thought about using the checkout_cart_add_product_complete observer to go through teh products and do some checks and add tax to the parent simple product. This works on adding the product to teh cart but any other cart operations trigger new collect totals (I think) which wipes out my newly added tax.
Has anyone got any ideas on how I might get the quote to keep these new tax amounts on the item level?